Hydroponic nutrient aeration and flow control device and system

ABSTRACT

The specification discloses a hydroponic nutrient aeration and flow control (NAFC) device and system, which both aerates and controls the flow of the hydroponic nutrient solution. The NAFC device has no moving parts. Each NAFC device mixes and aerates the nutrient from the nutrient reservoir with air and/or nutrient from one of the grow tanks. Each NAFC device additionally controls the flow of the aerated nutrient solution to the grow tank and the nutrient reservoir. The vertical position of the end of the nutrient return line in each grow tank may be adjusted to adjust the level of the nutrient solution within the grow tank.

BACKGROUND OF THE INVENTION

The present invention relates to hydroponics, and more particularly tohydroponic nutrient circulation systems.

Hydroponics is the method of growing plants without soil, using asolution of water and dissolved mineral and/or organic nutrients. Onlythe roots are immersed in the nutrient solution, and sometimes only thetips of the roots are immersed. Because soil nutrients are not availableto the plants, it is critical that all of the necessary nutrients beadded and maintained in the correct ratios in the nutrient solution.Hydroponic nutrient solutions must be monitored to ensure that nutrientconcentration, oxygen concentration, pH, and temperature are withindesired ranges.

Hydroponic systems are widely used by hobbyists and commercial growers.Growers employ a number of techniques to provide access to nutrients andto maintain the proper nutrient mixture for the plants.

Hobbyists with limited production needs may use static systems in whichthe plants are supported above a tank of nutrient solution with only theroots extending into the solution. In these systems, to assure the rootsare continuously immersed, water must be added to replace the water lossto transpiration and evaporation. The plants could die if the roots areout of the solution for only a few hours. Nutrient mixture ratios, pH,and temperature in each grow tank must be monitored and adjusted asnutrients are consumed by the plants and as nutrient concentrationchanges due to water level changes. Additionally, the plant roots musthave access to oxygen. It is common practice to bubble air through thenutrient solution so that the solution absorbs sufficient oxygen to meetplant needs. Air pumps and air stones, the same as those used inaquariums, are used for this purpose.

It is common for commercial growers and hobbyists, looking for moreefficient ways to grow larger crops, to use centralized reservoirs ofnutrient solution delivered to multiple grow tanks using pumps. Thesetypes of systems are referred to as “recirculation systems.” They aremore practical than static systems for growing large crops becausenutrient solutions can be monitored and maintained in a single locationrather than in each grow tank.

In one type of recirculation system, the solution from each growing tankis returned to the reservoir through gravity return pipelines. Automatickeep-full valves maintain reservoir level by adding water to thereservoir as the level drops. Proper nutrient mixture, pH, andtemperature can be maintained for all of the grow tanks in the networkby monitoring and adjusting the reservoir nutrient solution. The growtanks still require aeration, which typically is provided by a large airpump feeding a distribution manifold so that air may be delivered toeach grow tank. These systems require the grow tanks to be located abovethe level of the reservoir so that the gravity return lines can be used.

In another type of recirculation system, the multiple grow tanks and thereservoir all are at the same level. The grow pots are all connected toa common drain line so that they all have the same liquid level as inthe nutrient reservoir. A pump in the reservoir delivers nutrientsolution to each grow pot to provide a continuous supply of freshnutrient. Air is supplied by way of an air pump with air stones in eachgrow tank. Drainpipe size is generally large to assure that a commonlevel is maintained in all of the grow tanks and to assure thataggressive roots do not plug the drain ports in the grow tanks.

Systems that use multiple grow tanks connected at the bottom to a commonreservoir at the same level as the grow tanks must all operate at thesame liquid level as the reservoir and each other. This is not ideal ifit is desired to adjust the level of an individual grow tank toaccommodate different plants and root growth issues, or to use tieredbenches to locate grow tanks at different elevations. The hydroponicmethod known as Deep Water Culture is often used in these systems.Plants sit above the nutrient solution with just some of the rootsimmersed in the solution. Grow tanks may have one or more plants. Thesesystems are not suitable if roots require different nutrient levels orgrow tanks are at different elevations.

Certain aspects of recirculation systems are less than ideal. The drainpiping system must connect the reservoir directly with each grow tank.This requires leak-tight joints for grow tank gravity drain ports toconnect with the drain line. Particularly in systems where grow tanksare elevated relative to the reservoir, this can be a complex,three-dimensional network of pipes and joints, thereby addinginstallation expense and making modifications problematic. Reconfiguringpipelines requires a shutdown of the operation, potentially leavingroots exposed to air. Reconfiguring pipelines also can take significanttime, which adds to the risk of plant damage.

Aeration also presents problems. Aeration requires air pumps and lines,which adds cost. Air lines must be routed to all grow tanks adding tothe network cost and complexity.

There are other problems related to the specific type of grow tank. Thegrow tanks that employ the hydroponic system known as Net Film Technique(NFT) use a thin film of liquid nutrient flowing from one end to theother in the bottom of a trough-type tank. This type of grow tank iswidely used, for example, in commercial vegetable and herb operations.Many plants can grow side-by-side along the length of the trough. Theplants sit in holes in the cover of the trough with the tips of theirroots wetted by the thin layer of flowing nutrient. There are two basicproblems with such tanks. First, gravity drains in these tanks may allowall nutrient solution to drain out quickly in the event of a powerinterruption or pump failure. This can result in the loss of an entirecrop. Second, because these tanks are often rather long, the flow ofnutrient can get restricted by heavy root growth. If plants are notmonitored closely, the problem may not be found until significant damagehas occurred.

SUMMARY OF THE INVENTION

The present invention provides a hydroponic nutrient aeration and flowcontrol (NAFC) device and system, which both aerates and controls theflow of the nutrient solution.

The NAFC device has no moving parts. The NAFC device includes a nutrientsupply intake, a grow tank return intake, a nozzle communicating withthe nutrient supply intake, a mixing chamber in fluid communication withboth the nozzle and the grow tank return intake, an outlet port in fluidcommunication with the mixing chamber and aligned with the nozzle, and agrow tank supply outlet in fluid communication with the outlet port.Nutrient from the nutrient reservoir flows into the nutrient supplyintake, through the nozzle, and into the mixing chamber. Nutrient and/orair from the grow tank drain line is drawn through the grow tank returnintake and into the mixing chamber. The two nutrient flows and/or theair are admixed within the mixing chamber, and a portion of theadmixture is directed into the outlet port for delivery to the grow tankthrough the grow tank supply outlet.

The NAFC system includes an NAFC device within each nutrient supply lineto each grow tank. More specifically, the system includes a nutrientreservoir, a plurality of grow tanks, a nutrient supply system forsupplying nutrient from the reservoir to the grow tanks, a nutrientreturn system for returning nutrient from the grow tanks to the nutrientreservoir, and a plurality of NAFC devices—with each NAFC device withinone of the nutrient supply lines to one of the grow tanks.

In an alternative embodiment, the NAFC device may be used as ahydroponic nutrient aerator (i.e. without a flow control function).

The present invention provides significant improvement in hydroponicsystem efficiency. The nutrient solution can be mixed, aerated, andcirculated to multiple grow tanks from a nutrient reservoir; and thenutrient level in each grow tank may be controlled or adjustedindependently of the other grow tanks. The present invention alsoeliminates the need for common drain lines, improving safety andplumbing flexibility, and reducing cost. The present invention alsoeliminates the need for holes and leak-tight connections in the growtanks for nutrient circulation. Further, the present inventioneliminates the need for air pumps, reducing system component andinstallation costs.

These and other advantages and features of the invention will be morefully understood and appreciated by reference to the description of thecurrent embodiment and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a Type I hydroponic nutrient circulationsystem embodying the present invention.

FIG. 2 is a perspective view of a Type II hydroponic nutrientcirculation system embodying the present invention.

FIG. 3 is a perspective view of a pump and a manifold used in the Type Isystem.

FIG. 4 is an elevational view of the nutrient aeration and flow control(NAFC) device embodying the present invention.

FIG. 5 is an exploded sectional view of the NAFC device.

FIG. 6 is a sectional view of the NAFC device in a first mode ofoperation.

FIG. 7 is a sectional view of the NAFC device in a second mode ofoperation.

FIG. 8 is a sectional view of the aerator portion of the NAFC device andadditionally including a check valve.

FIG. 9 is a perspective view of the nutrient supply line and thenutrient return line for a grow tank.

FIG. 10 is a perspective view similar to FIG. 9 but with a differentfilter on the return line.

FIG. 11 is a perspective exploded view of the area within the circle XIin FIG. 9.

FIG. 12 is an elevational view of an alternative embodiment of the NAFCdevice.

FIG. 13 is a sectional view of the alternative embodiment of the NAFCdevice.

FIG. 14 is a perspective view of the alternative embodiment of the NAFCdevice connected to both nutrient supply and nutrient drainage lines.

FIG. 15 is a perspective view of a grow tank aerator assembly embodyingthe present invention.

FIG. 16 is a schematic illustration of the nutrient flow within theaerator 22.

FIG. 17 is a graph illustrating the relationship between nutrient flow,airflow, and nutrient pressure.

FIG. 18 is a perspective view of a saddle connection assembly includingthe second alternative embodiment of the NAFC device.

DESCRIPTION OF THE CURRENT EMBODIMENTS

Before the embodiments of the invention are explained, it is to beunderstood that the invention is not limited to the details of operationor to the details of construction; and the arrangement of the componentsset forth in the following description or illustrated in the drawings.The invention may be implemented in various other embodiments and may bepracticed or carried out in alternative ways not expressly disclosedherein.

In addition, it is to be understood that the phraseology and terminologyused herein are for the purpose of description and should not beregarded as limiting. The use of “including” and “comprising” andvariations thereof encompasses the items listed thereafter andequivalents thereof as well as additional items and equivalents thereof.Further, enumeration may be used in the description of variousembodiments. Unless otherwise expressly stated, the use of enumerationshould not be construed as limiting the invention to any specific orderor number of components. Nor should the use of enumeration be construedas excluding from the scope of the invention any additional steps orcomponents that might be combined with or into the enumerated steps orcomponents. Any reference to claim elements as “at least one of X, Y andZ” is meant to include any one or more of X, Y or Z individually, andany combination of any one or more of X, Y and Z, for example, X, Y, Z;X, Y; X, Z; and Y, Z.

Directional terms, such as “vertical,” “horizontal,” “top,” “bottom,”“upper,” “lower,” “inner,” “inwardly,” “outer” and “outwardly,” are usedto assist in describing the invention based on the orientation of theembodiments shown in the illustrations. The use of directional termsshould not be interpreted to limit the invention to any specificorientation(s).

Embodiments of the hydroponic nutrient aerator and flow control (NAFC)devices are illustrated in the drawings and designated 10 and 310.Before the NAFC devices are described in detail, it is noted the NAFCdevices may be used in two types of hydroponic installations. A “Type I”installation includes grow tanks arrayed in proximity to the nutrientreservoir. In this type of system, the NAFC devices 10 are mounted to amanifold connected to a reservoir pump. A “Type II” installationincludes a nutrient reservoir remote from the grow tanks. In this typeof system, the NAFC devices 310 are distributed throughout the system,with one NAFC device located near each grow tank.

I. Type I Hydroponic System

A Type I system is illustrated in FIG. 1 and generally designated 100.The system 100 includes a nutrient reservoir 102 and a plurality of growtanks 104. Although six grow tanks 104 are depicted, the system 100 mayinclude a greater or lesser number of grow tanks. The system 100 furtherincludes a submersible pump 106 and a manifold 108, shown in greaterdetail in FIG. 3. The pump 106 and the manifold 108 are submersed in thenutrient reservoir 102. An NAFC device 10 is mounted to each outlet ofthe manifold 108.

The grow tanks 104 may be different in size and number of plants, maysit at different elevations, and may operate at different liquid levels.The grow tanks 104 may individually employ different hydroponictechniques such as Deep Water Culture or Net Film Technique, as well asany other technique where it is desired to maintain a volume of nutrientsolution matching the condition of the nutrient reservoir. The growtanks 104 are not connected to each other by way of the common drainline. For simplicity, bucket covers, net pots, and/or other accessoriesare not shown in conjunction with the grow tanks 104, although the useof such component and accessories would be conventional as known tothose skilled in the art.

II. TYPE I NUTRIENT AERATOR AND FLOW CONTROL (NAFC) DEVICE

The NAFC device 10 will be described in conjunction with the Type ISystem 100. Each NAFC device 10 is part of an NAFC assembly 12, whichadditionally includes a supply hose or line 14 and a return hose or line16.

The NAFC assembly 12 provides independent circulation, aeration, andlevel control to the grow tank 104 to which the NAFC assembly isconnected. The NAFC assembly 12 delivers fresh nutrient and aerationthrough a supply hose 14 (see also FIG. 9) passing through a hole in thegrow tank cover (not shown) to the bottom of the grow tank 104. As thelevel of nutrient in the grow tank 104 rises, the NAFC assembly 12withdraws liquid from the surface of the nutrient and returns thewithdrawn nutrient to the reservoir 102 through a return hose 16, whichalso is installed in a hole in the grow tank cover. The level of thenutrient is maintained within the grow tank 104 at the lower end 18 ofthe return hose 16. The level of the nutrient can be easily adjusted bymoving the lower end 18 of the return hose 14 to the desired level.

Because the supply hose 14 and the return hose 16 extend over the top ofthe grow tank 104 and are secured in position by a clip 20, which inturn is removably securable to the rim of the grow tank, no holes arerequired in the grow tank. This arrangement assures there are no leaks,and that grow tanks 104 can be repositioned as needed without downtimeor plumbing expense. The incoming nutrient introduced into the bottom ofthe grow tank 104 lifts stale nutrient, so the stale nutrient can bedrawn off and returned to the nutrient reservoir 102. In this way, thenutrient within each grow tank 104 is circulated and maintained in thesame condition as the nutrient in the nutrient reservoir 102.

Further, the NAFC assembly 10 has an inherent aerating characteristic,which aerates the nutrient in the nutrient reservoir 102, and which alsomixes air and nutrient solution as the nutrient solution flows to thegrow tank 104. This eliminates the need for a separate air pump.

The NAFC device 10 is illustrated in FIGS. 4-7. The NAFC device 10 is amultiple-function, fluidic device with no moving parts. The NAFC device10 includes an aerator 22 and a receiver 24. The receiver 24 is closelyreceived and secured within the aerator 22. The aerator 22 includes anutrient inlet 26 and an air inlet 28 for receiving nutrient and airrespectively. The aerator 22 further includes a nozzle 30 and a mixingchamber 38. The nozzle 24 includes a receiver port 32 and an outlet 34.The receiver port 32 is aligned with the nozzle 30.

As illustrated in FIGS. 6-7, the nutrient inlet 26 is connected to themanifold 108; the grow tank return hose 16 is connected to the air inlet28; and the grow tank supply hose 14 is connected to the output 34.

As illustrated in FIG. 6, under the pump pressure at the inlet 26, ahigh velocity jet of nutrient solution exits the nozzle 30 into themixing chamber 38. In the first mode of operation, in which the end 18of the grow tank return hose 16 is above the liquid level in the growtank 104, air is aspirated into the region surrounding the nutrient jetin the mixing chamber 38. This enables the nutrient jet to remain as acoherent jet that travels in a straight path and impinges on thereceiver port 32. Both the liquid jet and some air enter the receiverport 32. This mix of fluids is conveyed to the grow tank 104 by way ofthe grow tank supply hose 14. During the travel to the grow tank 104,the air and the liquid mix; and oxygen is absorbed into the nutrientsolution. Some of the air aspirated into the nutrient jet bypasses thereceiver 32 and flows into the bypass chamber 41, through the bypassoutlet 43, and into the reservoir 102. In this way, the NAFC devices 10aerate the nutrient within the reservoir 102 as well as in the growtanks 104.

FIG. 7 illustrates the operation of the NAFC device 10 in a second modewhen the nutrient level in the grow tank 104 rises above the end 18 ofthe grow tank return hose 16 within the grow tank 104. The nutrientliquid is then aspirated and drawn back through the grow tank returnhose 16 and into the NAFC device 10 where it mixes with the nutrient jetin mixing chamber 38. This causes the nutrient jet to spread and contactthe curved wall 40 that surrounds the nutrient jet. The nutrient jet isdeflected by way of Coanda effect or wall attachment effect, and isdiverted away from the receiver port 32. Flow to the grow tank isdiminished or even stopped completely, so that the flow of liquid in thegrow tank return hose 16 causes the grow tank level to drop back to theend 18 of the hose at which point air is again aspirated and anothercycle of filling is initiated.

The NAFC device 10 cycles between the mode illustrated in FIG. 6 and themode illustrated in FIG. 7 continue as long as the pump operates. Thismaintains the level in the grow tank at the end 18 of the grow tankreturn hose 16 and also circulates aerated nutrient. Complete turnovertime for a given volume of grow tank nutrient can be controlled by theselection of the NAFC device nozzle diameter and the pump pressure. Forexample, an NAFC device 10 with a nozzle diameter of 0.082 inches and apump pressure of 6 psi will cycle the nutrient solution in a five-gallongrow tank twice in one hour. Pumps may be run continuously or on atimer.

The aeration of the nutrient stream within the NAFC device 10 isschematically illustrated in FIG. 16. Nutrient N enters the devicethrough the intake port 26 and passes through the nozzle 30 to createthe jet. The jet mixes with air received through the intake port 28 andthe aerated nutrient N′ results.

FIG. 17 is a graph illustrating the nutrient flow and the airflowthrough the NAFC device 10 at various nutrient head pressures. Thenutrient flow exceeds the airflow below a nutrient head pressure ofapproximately 10 Ft. And the nutrient flow is less than the airflowabove that nutrient head pressure.

Because the end of the grow tank supply hoses are submerged, ananti-siphon means is provided to introduce air into the hoses when thepump is off. Anti-siphon means may be a small hole 42 in the side of thehose above the nutrient level as illustrated in FIG. 11.

Further, because the grow tank return hose 16 can potentially besubmerged at its end 18 when the pump turns off, a check valve 44 may beplaced in the intake port 28 to prevent the contents of the nutrienttank from siphoning into the grow tank if the grow tank nutrient levelis below the nutrient reservoir level. If the grow tank nutrient levelis above the nutrient reservoir level when the pump shuts off, the growtank nutrient level will drop to the set point which is the verticalposition of the end 18 of the hose 16 in the grow tank. The check valve44 is preferably a duckbill type, but other check valves could be used.A low opening differential pressure is preferred so the aspiration ofnutrient from the grow tank can occur at the fastest rate.

FIGS. 9 and 10 illustrate the mounting of the hoses 14 and 16 on thegrow tank 104. A bracket 20 attaches to the rim 46 of the grow tank 104and directs the hoses downwardly into the grow tank. The supply hose 14extends to a low level (as described above), and the end 19 preferablyis positioned near the horizontal center of the grow tank 104, so thatnutrient and air are introduced near the middle of the lower portion ofthe grow tank.

As illustrated in FIG. 9, the end 18 of the return hose 16 includes afilter 46 that prevents roots from entering the hose 16 and potentiallyblocking the hose. The filter 46 preferably is a porous plasticmaterial. A porous plastic material is preferred over meshes or screensbecause roots can penetrate the openings in those types of filters. Thereturn hose 16 may be slid within the bracket 20 so that the end 18 andthe filter 46 may be placed at the desired nutrient solution level forthe grow tank 104. The desired nutrient level may differ between plantpot sizes and may also change as the roots develop. In some cases, asthe roots grow, the level will be set lower so that the root tips remainsubmerged while the root mass may be exposed to air to improve oxygenabsorption. Preferably, the return hose 16 is marked with a graduatedscale indicating the depth of the nutrient liquid level. The systemholds the liquid level accurately at the location of the end 18 of thereturn hose 16.

FIG. 10 illustrates a tubular filter or equalizer tube 46 a, which maybe used in place of the filter 46 illustrated in FIG. 9. The return hose16 is located inside of the tubular filter 46 a with its lower end 18 atthe level set point. The inside diameter of the tubular filter 46 a islarger than the outer diameter of the return hose 16. The porosity ofthe tubular filter 46 a enables the liquid level inside the tubularfilter to equalize with the grow tank level. The tubular filter 46 aoffers increased filter area for longer filter life.

III. TYPE II HYDROPONIC SYSTEM

A Type II System is illustrated in FIG. 2 and generally designated 200.The system 200 includes a nutrient reservoir 202 and a plurality of growtanks 204. The nutrient solution within the nutrient reservoir 202 isdistributed to the grow tanks 204 by way of a network of pressure pipes210 and return pipes 212. The pressure and return pipes 210, 212 can befitted with quick disconnects at each grow tank location so that eachNAFC device 10 may be snapped into or removed from the pipes withoutinterrupting the system operation. The reservoir 202 and the grow tanks204 may be similar to, or different from, the reservoir 102 and the growtanks 104 respectively.

IV. TYPE II NUTRIENT AERATOR AND FLOW CONTROL (NAFC) DEVICE

FIGS. 12 and 13 illustrate the NAFC device 310 for a Type II hydroponicsystem. The NAFC device 310 includes an aerator 322 and a receiver 324.

The aerator 322 is highly similar structurally and functionally to theaerator 22 previously described. The elements in the aerator 322 thatcorrespond to elements in the aerator 22 are identified by thecorresponding number preceded by the digit “3”. Accordingly, the inletport 326 corresponds to the inlet port 26, and so forth. The primarydifference between the aerator 322 and the aerator 22 is that the inletport 326 is threaded to receive a mating threaded component.

The receiver 324 is highly similar functionally to the aerator 22previously described. The elements in the receiver 324 that correspondto elements in the receiver 24 are identified by the correspondingnumber preceded by the digit “3”. Accordingly, the receiver port 332corresponds to the receiver port 32, and so forth. Two differencesbetween the receiver 324 and the receiver 24 are that (a) the grow tanksupply line port 334 extends transversely from the NAFC device 310 and(b) the outlet 335 includes an external fitting 337.

FIG. 14 illustrates the incorporation of the NAFC device 310 into theType II system 200. The pressure line 210 is fitted with a tee 206 ateach growing tank 204 along with a quick coupling 208 having a shut-offvalve (not visible). Similarly, the drain line 212 is fitted with a tee214 along with a quick coupling having a shut-off valve (not visible).All of these components are fluidly and securely interconnected usingtechniques well known to those skilled in the art.

The valves enable the NAFC unit 310 to be installed and removed withoutshutting off the pump. This enables modifications and service to beperformed on individual growing stations without interrupting systemoperation. The drain line is always filled with nutrient solution at thereservoir head pressure. The check valves prevent the nutrient fromleaking out when the NAFC device 310 is not installed.

Preferably, the NAFC device 310 is fitted with male quick-connectfittings. When installing the NAFC into a pressurized line, the NAFCgrow tank connections are made first. Then the NAFC outlet is connectedto the drain line. Then the NAFC inlet fitting is inserted into thequick coupler, which opens the shut-off valve, and operation begins.When removing the NAFC device 310, the quick coupling is firstdisconnected from the pressurized line, and then the NAFC device isdisconnected from the drain coupling and the grow tank tubes.

FIG. 18 illustrates an alternative embodiment to the arrangementillustrated in FIG. 14 for connecting the NAFC device 310 in a Type IIsystem 200. The FIG. 18 design incorporates pipe saddles 510 that may beattached to the nutrient supply line 210 and the nutrient drain line212. The saddles 510 include sprinkler-system, snap-on, self-tappingtees 512 and 514 to connect the NAFC device 310 to the lines 210 and 212respectively. The tees 512 and 514 simplify and reduce installationlabor because the self-tapping tool is incorporated into the saddle 510.The saddles 510 can be added to an existing pipe run without drainingthe pipes. One suitable saddle is that made and sold by King Innovationsfor use in underground sprinkler systems.

V. HIGH EFFICIENCY AERATOR

Many hydroponic growers would like to improve the aeration in theirrecirculation systems. Air pumps, air stones, and associated airlinesrequire maintenance and may not always provide sufficient oxygen to theplant roots. Accordingly, there is a need for improved aeration in manyexisting hydroponic recirculation systems.

There are alternatives to air pumps for aeration, but these alternativescreate problems when used in multiple tank recirculation systems. Pumpsfitted with a venturi aspirate air and mix it with nutrient. These pumpsare too large and too expensive to connect to each grow tank tocirculate individual nutrient solution. If a large, single-venturi pumpis used to augment nutrient aeration and circulation, such a pump mayincrease the flow rate beyond the grow tank drain capacity or notprovide sufficient oxygen if flow is limited. There are also aeratorsused for marine live wells and bait wells that are designed to operatewith 500 GPH to 750 GPH or more. These marine aerators are impracticalto circulate individual grow tank nutrient with their own pump, andwould be problematic if mounted to each grow tank and supplied by asystem pump. At high enough flow rate to provide enough air, the flowinto the grow tanks would exceed drain capacity, leading to unevennutrient levels and potentially even overflows.

The NAFC has a mode of configuration and operation ideal for thissituation. When the receiver 24 is not installed in the aerator 22, theNAFC device may operate as a high-efficiency, low-liquid-flow-rateaerator. Configured in this mode, and designated NAFC-A, an aerator 22may be mounted to each grow tank and supplied by a central recirculationpump. The individual aerators 22 have a relatively low flow rate, sogrow tank capacity will not be exceeded. However, the aerator 22generates a high velocity liquid jet, which creates a strong aspirationof air into the jet. The strength of the aspiration effect is reflectedby comparing the strength of the vacuum head created by the NAFC-A withother aerators at their normal operating flow rate. The aerator 22operating at 10 Ft. of head develops a liquid flow rate of 0.65 GPM or39 GPH. This is a manageable flow rate for a typical 6-gallon grow tankdrain system. This aerator produces a turnover rate of once every 6minutes for a tank filled with 4 gallons of nutrient.

FIG. 15 illustrates one embodiment of a grow tank aerator assembly 400incorporating the NAFC-A aerator 422. The assembly 400 includes anaerator 422, an air supply pipe 402, a nutrient inlet port 426, adischarge tube 404, and a U 406. Nutrient is received through intakeport 426, and the nutrient flows through the aerator 422 to be aeratedas described above. The aerated nutrient solution is outputted into thetube 404 for discharge through the U 406 into the grow tank (not shownin FIG. 15). The U 406 enables the aerator assembly 400 to be mounted onthe rim of a grow tank.

VI. CONCLUSION

The NAFC devices provide unique features to improve the performance ofhydroponic nutrient circulation systems. The devices aerate the nutrientsolution without the need for air pumps, air stones, and air tubeplumbing. The devices circulate aerated nutrient solution withoutgravity drains or a common drain line connecting grow tanks and thenutrient reservoir. The devices provide individual grow tanks withadjustable level control without the need for mechanical or electricalvalves. The devices can empty grow tanks without requiring drain holesin the grow tanks. The devices enable grow tanks to be mounted atindividual elevations. The devices enable different size grow tanks tobe serviced from the same nutrient reservoir. The devices, whenappropriately sized, provide rapid cycling (i.e. turnover) of grow tanknutrient solution. The devices may work with continuous or timed pumpoperation. The devices may be used with the most popular types ofexisting hydroponic systems. The devices enable an individual grow tankin a network to be serviced (i.e. moved, emptied, cleaned, replanted,etc.) without interrupting operation of the other tanks in the network.

The aerator version (i.e. the NAFC-A device) delivers high aeration toindividual grow tanks without exceeding the existing drain capacity ofthe systems.

The above descriptions are those of current embodiments of theinvention. Various alterations and changes can be made without departingfrom the spirit and broader aspects of the invention as defined in theappended claims, which are to be interpreted in accordance with theprinciples of patent law including the doctrine of equivalents.

This disclosure is illustrative and should not be interpreted as anexhaustive description of all embodiments of the invention or to limitthe scope of the claims to the specific elements illustrated ordescribed in connection with these embodiments. For example, and withoutlimitation, any individual element(s) of the described invention may bereplaced by alternative elements that provide substantially similarfunctionality or otherwise provide adequate operation. This includes,for example, presently known alternative elements, such as those thatmight be currently known to one skilled in the art, and alternativeelements that may be developed in the future, such as those that oneskilled in the art might, upon development, recognize as alternatives.

Further, the disclosed embodiments include a plurality of features thatare described in concert and that might cooperatively provide acollection of benefits. The present invention is not limited to onlythose embodiments that include all of these features or that provide allof the stated benefits, except to the extent otherwise expressly setforth in the issued claims. Any reference to claim elements in thesingular, for example, using the articles “a,” “an,” “the” or “said,” isnot to be construed as limiting the element to the singular.

1. A hydroponic nutrient circulation system comprising: a nutrientreservoir; a plurality of grow tanks; a nutrient supply system forsupplying nutrient from the nutrient reservoir to the grow tanks, thenutrient supply system including a nutrient supply line extending intoeach grow tank; a nutrient return system for returning nutrient from thegrow tanks to the nutrient reservoir, the nutrient return systemincluding a nutrient return line extending into each grow tank; an airsupply line extending into each grow tank; and a plurality of aerationdevices, each aeration device within one of the grow tanks, each aeratordevice including: a nutrient supply intake connected to the associatednutrient supply line; an air intake connected to the associated airsupply line; a nozzle in fluid communication with the nutrient supplyintake; a mixing chamber in fluid communication with the nozzle and withthe air intake; and an outlet in fluid communication with the mixingchamber.